Kyle Isom
b26478d47b
Runs the MCP v2 master as a systemd service on rift. Uses ConditionPathExists so the unit is a no-op on worker nodes (like orion) that import mcp.nix but don't have the binary. Starts after mcp-agent.service. Security hardened like the agent but with ProtectHome=true (master doesn't need /run/user). Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
96 lines
2.9 KiB
Nix
96 lines
2.9 KiB
Nix
# MCP (Metacircular Control Plane) agent user and configuration.
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#
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# Creates a dedicated 'mcp' system user with rootless podman support
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# and a systemd service for the agent daemon.
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{ pkgs, ... }:
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let
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mcpUid = 995;
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in
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{
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users.users.mcp = {
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isSystemUser = true;
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uid = mcpUid; # Pin UID so systemd Environment references stay stable.
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group = "mcp";
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home = "/srv/mcp";
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shell = pkgs.shadow; # nologin equivalent
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subUidRanges = [{ startUid = 100000; count = 65536; }];
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subGidRanges = [{ startGid = 100000; count = 65536; }];
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extraGroups = [ "systemd-journal" ];
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linger = true;
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};
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users.groups.mcp = {};
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# MCP Master — multi-node orchestrator (v2).
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# Runs on the master node only (rift). Coordinates deployments across
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# agents, manages edge routing, and maintains cluster state.
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# Uses ExecStartPre to skip startup if the binary is absent (safe on
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# worker nodes that import this module but don't run the master).
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systemd.services.mcp-master = {
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description = "MCP Master";
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after = [ "network-online.target" "mcp-agent.service" ];
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wants = [ "network-online.target" ];
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wantedBy = [ "multi-user.target" ];
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unitConfig = {
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ConditionPathExists = "/srv/mcp-master/mcp-master";
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};
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serviceConfig = {
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Type = "simple";
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ExecStart = "/srv/mcp-master/mcp-master server --config /srv/mcp-master/mcp-master.toml";
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Restart = "on-failure";
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RestartSec = 5;
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NoNewPrivileges = true;
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ProtectSystem = "full";
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ProtectHome = true;
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PrivateTmp = true;
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PrivateDevices = true;
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ProtectKernelTunables = true;
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ProtectKernelModules = true;
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RestrictSUIDSGID = true;
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LockPersonality = true;
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RestrictRealtime = true;
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ReadWritePaths = [ "/srv/mcp-master" ];
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};
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};
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systemd.services.mcp-agent = {
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description = "MCP Agent";
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after = [ "network-online.target" ];
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wants = [ "network-online.target" ];
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wantedBy = [ "multi-user.target" ];
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serviceConfig = {
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Type = "simple";
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ExecStart = "/srv/mcp/mcp-agent server --config /srv/mcp/mcp-agent.toml";
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Restart = "on-failure";
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RestartSec = 5;
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User = "mcp";
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Group = "mcp";
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Environment = [
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"HOME=/srv/mcp"
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"XDG_RUNTIME_DIR=/run/user/${toString mcpUid}"
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"PATH=/run/current-system/sw/bin:/usr/local/bin"
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];
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NoNewPrivileges = true;
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ProtectSystem = "full"; # "strict" blocks /run/user; "full" protects /usr and /boot
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# ProtectHome makes /run/user inaccessible, which breaks rootless podman.
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# The agent's home is /srv/mcp (not /home), so this is acceptable.
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ProtectHome = false;
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PrivateTmp = true;
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PrivateDevices = true;
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ProtectKernelTunables = true;
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ProtectKernelModules = true;
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RestrictSUIDSGID = true;
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LockPersonality = true;
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RestrictRealtime = true;
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ReadWritePaths = [ "/srv" ];
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};
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};
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}
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